Waste materials from various sources contain blends of oils, grease, protein, fibers, minerals and water at varying percentages. Examples include: grease trap materials, wood processing byproducts, animal processing waste such as animal blood and animal meat originating from slaughterhouses, and animal manure that originates from farms. The waste byproducts contain valuable components that have beneficial uses if recovered from these waste materials. Biomass materials may be used as animal feed, minerals may be used in fertilizers, and lignin, which is a component of wood, may be used as a binder, an emulsifier or a dispersant. Additionally, these waste streams contain large amount of water that, if recovered, has a variety of uses including irrigation and drinking.
In most cases, large solids are separated from waste material streams by means of screens, such as a screw press or a multidisc press. In subsequent steps, additional insoluble materials may be separated from the water through air floatation devices, clarifiers or settling lagoons. Most such processes however, leave an effluent stream that contains between from about 1.5% to about 4%, which cannot be removed from the water economically by conventional processes.
It would therefore be desirable to provide a process to separate these residual solid materials from effluent stream that would provide a drinkable water stream and recycle the solid materials for beneficial uses such as fertilizers.